Application Examples
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INTERRUPT HANDLERS
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; ONLY ONE SERIAL INTERRUPT HANDLER IS ILLUSTRATED.
OTHER
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HANDLERS CAN BE ADDED HERE AS NEEDED.
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CODE
SEGMENT
PARA
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ASSUME
CS:CODE,SS:STACK,DS:DATA,ES:NOTHING
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SERIAL_8250
PROC
; THIS PROCEDURE HANDLES INTERRUPTS GENERATED BY THE
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8259A PIC ON THE ZT 8840.
THE INT_FLAG LOCATION
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WILL RECORD THAT THE INTERRUPT WAS RECEIVED WITH
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A ZERO VALUE. IT IS ASSUMED THE FLAG IS INITIALLY 0FFH.
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; INPUTS:
NONE
; OUTPUTS:
INT_FLAG - 0H
; CALLS:
NONE
; DESTROYS:
NONE
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PUSH
AX
PUSH
DX
MOV
INT_FLAG,0
; RECORD THAT THE INT WAS RECV’D
MOV
AL,0
PUT
UART1+PORT_INTEN ; DISABLE FURTHER INTERRUPTS
MOV
AL,OCW2_8809A
; SEND EOI’S
PUT
PORT_A_8809A
MOV
AL,OCW2_8840
MOV
DX,PORT_A_8840
OUT
DX,AL
POP
DX
POP
AX
IRET
SERIAL_8250
ENDP
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